/*
* Conditions Of Use 
* 
* This software was developed by employees of the National Institute of
* Standards and Technology (NIST), an agency of the Federal Government.
* Pursuant to title 15 Untied States Code Section 105, works of NIST
* employees are not subject to copyright protection in the United States
* and are considered to be in the public domain.  As a result, a formal
* license is not needed to use the software.
* 
* This software is provided by NIST as a service and is expressly
* provided "AS IS."  NIST MAKES NO WARRANTY OF ANY KIND, EXPRESS, IMPLIED
* OR STATUTORY, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTY OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, NON-INFRINGEMENT
* AND DATA ACCURACY.  NIST does not warrant or make any representations
* regarding the use of the software or the results thereof, including but
* not limited to the correctness, accuracy, reliability or usefulness of
* the software.
* 
* Permission to use this software is contingent upon your acceptance
* of the terms of this agreement
*  
* .
* 
*/
/*******************************************************************************
* Product of NIST/ITL Advanced Networking Technologies Division (ANTD).        *
*******************************************************************************/
package gov.nist.javax.sip.header;
import javax.sip.header.*;
import javax.sip.InvalidArgumentException;

/**
 * MaxForwards SIPHeader
 *
 * @version 1.2 $Revision: 1.7 $ $Date: 2007/02/12 15:19:22 $
 *
 * @author M. Ranganathan   <br/>
 * @author Olivier Deruelle <br/>
 * 
 */
public class MaxForwards extends SIPHeader implements MaxForwardsHeader {

	/**
	 * Comment for <code>serialVersionUID</code>
	 */
	private static final long serialVersionUID = -3096874323347175943L;
	/** maxForwards field.
	 */
	protected int maxForwards;

	/** Default constructor.
	 */
	public MaxForwards() {
		super(NAME);
	}

  public MaxForwards( int m ) throws InvalidArgumentException {
		super(NAME);
		this.setMaxForwards( m );
	}

	/** get the MaxForwards field.
	 * @return the maxForwards member.
	 */
	public int getMaxForwards() {
		return maxForwards;
	}

	/**
	     * Set the maxForwards member
	     * @param maxForwards maxForwards parameter to set
	     */
	public void setMaxForwards(int maxForwards)
		throws InvalidArgumentException {
		if (maxForwards < 0 || maxForwards > 255)
			throw new InvalidArgumentException(
				"bad max forwards value " + maxForwards);
		this.maxForwards = maxForwards;
	}

	/**
	     * Encode into a string.
	     * @return encoded string.
	     *
	     */
	public String encodeBody() {
		return encodeBody(new StringBuffer()).toString();
	}

	protected StringBuffer encodeBody(StringBuffer buffer) {
		return buffer.append(maxForwards);
	}

	/** Boolean function
	 * @return true if MaxForwards field reached zero.
	 */
	public boolean hasReachedZero() {
		return maxForwards == 0;
	}

	/** decrement MaxForwards field one by one.
	 */
	public void decrementMaxForwards() throws TooManyHopsException {
		if (maxForwards > 0)
			maxForwards--;
		else throw new TooManyHopsException ("has already reached 0!");
	}
	
	public boolean equals(Object other) {
		if (this==other) return true;
		if (other instanceof MaxForwardsHeader) {
			final MaxForwardsHeader o = (MaxForwardsHeader) other;
			return this.getMaxForwards() == o.getMaxForwards();
		}
		return false;
	}
}
